With the advent of the Clean Air Act of 1990, the law now mandates the elimination of emissions (leaks) of CFC/HCFC/HFC refrigerant into the atmosphere from air conditioning and refrigeration systems, as well as emissions (leaks) of pollutant gases from chemical plants and the like. The federally-mandated ban on producing the CFCs after Jan. 1, 1996, will cause a Severe shortage of high cost CFCs in order to maintain the Operation of the equipment dependent on those CFCs that will be in existence for the next 15-20 years. Therefore, it will be imperative to seal leaks to maintain the efficacy of the air conditioning and refrigeration equipment for the sake of economy, as well as to conform to the law. The new alternative HFC refrigerants are also considered to have a global warming effect; therefore, they also should not be emitted (leaked) into the atmosphere.
At today's rate of usage, one year of refrigerant fluid leaks costs about $1.2 billion in lost refrigerant which amounts to 336,000,000 lbs. escaping into the ozone layer with an average unit leaking about 30% of its charge per year.
Excellent sealants according to Packo et al U.S. Pat. Nos. 4,304,805; 4,379,067; 4,237,172; 4,331,722 and 4,442,015 have previously been developed and have served the industry very well. In one commercially successful embodiment according to U.S. Pat. No. 4,379,067, a sealant for stopping leaks in air conditioning and refrigeration circuits comprises a mixture of approximately 30 wt %, bis-(dimethyl amino)methyl silane (BISDAMS), about 60 wt % vinyl trimethoxysilane and about 10 wt % tetramethoxy silane (TMOS). Tetraalkoxy silanes, such as TMOS, have been found useful in this composition as well as other sealant compositions in accordance with the aforementioned patents because the tetraalkoxy silane improves the integrity and toughness of the seal. However, such tetraalkoxy silanes, including TMOS, being derivatives of methyl Silicate, have the problem of toxicity.